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August 20, 2024
ADHD is associated with deficits in cognitive functions. These include such executive functions as reaction time, motor and interference inhibition, sustained attention, and working memory.
To what extent can ADHD medications compensate for such deficits? A recent meta-analysis by a European study team has explored this question. It suggests that while medication cannot completely reverse deficits in executive functions, it can lead to significant improvements.
Based on consistent evidence from many randomized double-blind controlled trials (RCTs) measuring behavioral improvements, first line treatment for ADHD is with stimulant medication while second-line treatment (for stimulant non-responders, or poor tolerability) is with non-stimulant medication (atomoxetine, viloxazine, guanfacine and clonidine).
This systematic literature search yielded eighteen RCTs, not all of which covered the same executive functions or medicines.
Meta-analyses yielded the following results:
Eleven RCTs, encompassing 925 participants, found a small-to-medium effect size improvement with methylphenidate. Variation (heterogeneity) among these studies was moderate, and there was no sign of publication bias.
Four RCTs with a total of 286 participants similarly reported a small-to-medium effect size improvement with atomoxetine. Again, heterogeneity was moderate, with no indication of publication bias.
Sixteen RCTs, with a combined 1,335 participants, found a medium effect size improvement with methylphenidate. Heterogeneity was moderate, and there was some indication of publication bias. No effort was made to correct for publication bias.
Three RCTs, encompassing 254 persons, found a medium effect size improvement with atomoxetine. Heterogeneity was moderate, with no evidence of publication bias.
Thirteen RCTs, with a total of 1,201 participants, found a small-to-medium effect size improvement with methylphenidate. Heterogeneity was moderate, with marginal indication of publication bias.
Six RCTs with a combined 753 individuals, reported a medium effect size improvement with atomoxetine. Heterogeneity was high, but there was no evidence of publication bias.
Nine RCTs, with a total of 1,025 participants, found a small-to-medium effect size improvement with methylphenidate. Heterogeneity was moderate, with no indication of publication bias.
Three RCTs with a combined 132 individuals, reported a statistically nonsignificant small-to-medium effect size improvement with atomoxetine. Heterogeneity was moderate, with no indication of publication bias. The nonsignificant outcome may have been due to the much smaller number of participants.
The team concluded, “these meta-analyses of chronic effects of stimulants and non-stimulants on executive functions in ADHD showed significant improvements with both methylphenidate and with atomoxetine in all cognitive domains tested with relatively similar effect sizes, and no statistical differences between them. The findings hence suggest comparable positive effects of both ADHD medication types on the most relevant executive functions in ADHD, suggesting for the first time that stimulant and non-stimulant ADHD medications, when taking [sic] longer-term, not only improve behavioural symptoms of ADHD, but also improve executive function performance, and to a similar degree.”
Ferdous Isfandnia, Sahid El Masri, Joaquim Radua, and Katya Rubia, “The Effects of Chronic Administration of Stimulant and Non-stimulant Medications on Executive Functions in ADHD: A Systematic Review and Meta-Analysis,” Neuroscience and Biobehavioral Reviews (2024), https://doi.org/10.1016/j.neubiorev.2024.105703.
While ADHD is a developmental disorder, shaped by biology and genetics, growing evidence shows that it is also influenced by the social and environmental conditions in which children grow up. Research on the social determinants of health emphasizes that development is shaped not only by biology but also by factors such as family income, access to healthcare, neighborhood safety, and material stability. These factors can affect both how developmental challenges appear and whether they are recognized and diagnosed.
Children facing socioeconomic disadvantage consistently show higher risks of developmental and behavioral difficulties. Chronic stress linked to poverty – including financial strain, food insecurity, and limited access to resources – has been associated with problems in attention, emotional regulation, and daily functioning. Children from lower-income families also tend to experience more severe ADHD symptoms and face greater barriers to ongoing care.
Neighborhood conditions matter as well. Unsafe environments can limit opportunities for play and social interaction while increasing caregiver stress, all of which may influence children’s behavior and development. Material hardships, such as food insecurity, can further undermine stability at home.
The Study:
The study analyzed six years of data from the National Survey of Children’s Health (2018–2023), covering more than 205,000 U.S. children aged 3 to 17. After accounting for age, sex, race and ethnicity, region, family structure, survey year, and other social factors, the researchers found a strong income gradient in ADHD prevalence. Compared with children in households earning at least four times the federal poverty level, those in households earning two to four times that level had 28 percent higher odds of ADHD. Odds rose to 70 percent higher in households earning one to two times the poverty level, and more than doubled among children living below the poverty line.
Parental education showed a similar pattern. Compared with children whose parents had completed college, ADHD odds were 20 percent higher among those whose parents had some college education, 40 percent higher among those whose parents had only a high school education, and 80 percent higher among those whose parents had not finished high school.
Children living in unsafe neighborhoods had nearly twice the odds of ADHD compared with those in safe neighborhoods, and food insecurity was also linked to almost double the odds.
By contrast, race and ethnicity alone were associated with much smaller differences. Compared with non-Hispanic White children, children in non-Hispanic Black households had an 18 percent higher likelihood of ADHD, while children in Hispanic households had a 25 percent lower likelihood. No substantial differences were observed for children from other or multiracial households.
Conclusion and Takeaway:
The study team concluded, “Children living in lower-income households, experiencing food insecurity, and residing in unsafe neighborhoods consistently showed higher prevalence and higher adjusted odds of both conditions. … Overall, these findings reinforce the need to view neurodevelopmental disorders within a broader social and structural framework.”
It should be noted that this study is not aiming to name social factors as direct causes of ADHD. Rather, it points to socioeconomic disparities as contributing to the way ADHD develops and how it is treated. This type of research, as well as acknowledging barriers to care, is crucial for clinicians, counselors, teachers, etc., to consider when working with youth with ADHD.
Counting umbilical cord vessels is standard in prenatal ultrasounds and confirmed at birth. Single umbilical artery (SUA) occurs in about 1 in 200 cases, with roughly 10% associated with anomalies, including central nervous system defects. Isolated SUA (iSUA) means one artery is missing without other structural issues.
Research on SUA, especially isolated iSUA, and childhood neurodevelopmental disorders (NDD) is limited and inconclusive. iSUA is linked to preterm birth and small-for-gestational age (SGA), both of which are NDD risk factors.
This Norwegian nationwide population study aimed to assess NDD risk in children with iSUA at birth, the influence of sex, and how preterm birth and SGA mediate this relationship.
The nation’s universal single-payer health insurance and comprehensive population registries made it possible to analyze all 858,397 single births occurring from 1999 to 2013, with follow-up continuing through 2019. Among these cases, 3,532 involved iSUA.
After adjusting for confounders such as parental age, education, and maternal health factors, no overall link was found between iSUA and later ADHD diagnosis. However, females with iSUA had about a 40% higher risk of subsequent ADHD compared to those without iSUA, even after adjustment.
The authors concluded, “The present study indicates that iSUA is weakly associated with ID [intellectual disability] and ADHD, and these associations are influenced by sex. This association is mediated negligibly through preterm birth and SGA. The associations were not clinically significant, and the absence of associations of iSUA with other NDD is reassuring. This finding can be useful in the counseling of expectant parents of fetuses diagnosed with iSUA.”
Refractive errors, such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (distorted vision due to irregular curvature of the eye or lens), are common worldwide. These conditions affect 12%, 5%, and 15% of children, and rise significantly in adults to 26.5%, 31%, and 40%. Additionally, strabismus (misalignment of the eyes) and amblyopia (reduced vision in one eye from uneven image formation, often linked to strabismus) occur globally at rates of 2% and 1.4%, respectively.
Visual impairment can affect children’s concentration in school, and studies suggest a link between eye disorders and ADHD.
To investigate this relationship, two researchers – one based in the US and the other in Israel –carried out a nationwide retrospective cohort study using electronic medical records of all insured individuals aged 5 to 30 who were part of Maccabi Health Services, Israel’s second largest health maintenance organization, between 2010 and 2022.
Of over 1.6 million insured members (2010–2020), inclusion/exclusion criteria and propensity score matching for age and sex were applied, along with a one-year wash-out period between the first eye diagnosis and ADHD diagnosis. In total, 221,707 cases were matched with controls without eye disorders at a 1:2 ratio, resulting in a cohort of 665,121 participants.
Overall, those with any previous eye diagnosis were 40% more likely to have a subsequent ADHD diagnosis. This was slightly higher for females (45%) than for males (35%). It was also slightly higher for children and adolescents (42%) than for adults (37%).
More specifically:
The authors concluded that eye disorders are associated with ADHD. They noted these associations were more marked in females and children and adolescents, although, as noted above, those differences were small. They recommended that primary care providers and neurologists consider risk stratification for early screening, and that ophthalmologists refer high-risk patients for ADHD evaluation.
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